The present invention relates to an X-ray CT (Computed Tomography) apparatus and an X-ray tube, and particularly to an X-ray CT apparatus which uses multiple X-rays of different energy levels and to an X-ray tube which is suitable for this X-ray CT apparatus.
An X-ray CT apparatus performs the qualitative tomographic imaging of particular substances by using multiple X-rays of different energy levels. Separation of X-ray energy is based on the use of a multi-layer X-ray detector having inter-layer filters, and X-ray detection signals of different energy levels are obtained from individual layers (refer to patent publication 1 for example).
[Patent publication 1] Japanese Patent Unexamined Publication No. Hei 6(1994)-277208 (FIGS. 1 and 2 on pages 3 and 4)
The above-mentioned X-ray CT apparatus needs a special detector having filters, i.e., multi-layer X-ray detector, and the filters which are interposed between layers need to be large in area enough to cover the whole sensing surface of the X-ray detector.